Automatic resistance testing apparatus



Nov. 14, 1933. -A. c. SELETZKY 1,935,487

AUTOMATIC RESISTANCE TESTING APPARATUS Filed Aug. 28, 1931 4 Sheets-Sheet l F/G. Z

In vanfbr Nov. 14, 1933. c, SELETZKY 1,935,487

AUTOMATIC RESISTANCE TESTING APPARATUS Filed Aug. 28, 1931 4 Sheets-Sheet 2 Nov. 14, 1933. A. c. SELETZKY .AUTOMATIC RESISTANCE TESTING APPARATUS Filed Aug. 28, 1931 4 Sheets-Sheet 3 [mm/for @a me Nov. 14,1933. A. c. SELETZKY 1,935,437

AUTOMATIC RESISTANCE TE STING APPARATUS Filed Aug. 28. 1931 4 Sheets-Sheet 4 Patented Nov. 14, 1933 APPARATUS v I Ahat'oli QSltz'ky, oievelana, Ohio h 7 Application August 28,- 19 31 S erial N0. 560,64?

Y This mventien relates to aii ajltom'ati 'res t fi apparatus for the testihfg of aiti'cies 'mad'e of Gondiicting materials and; is pan ticulaflyeoricerned with an automatic appaiatus fo r' the deteotior'iof spurious coins. A gen liijne coi i has a certain e1ectrica1 resistance as measured between-two g'i'veh poihts I'1' the Coin. The metals used ihthe manufacture of counter fei't thins-cause the resistances of the coi ntefr wfeit coins to be different from the resistances qf'gentiine goihs of the same denomina tion The Comparison of the resistance 'of an 'li'rikhown coin with that'of a genuine coin of the same de nomination oi-Ters a method of detection which i'sindependent'df'the weight, dimensions oif mag:- n'eti'cj properties of the coin and deper' jdsonl'y upon the value ofspecificelectrical resistance of the materiai from Whih the coin has, been .M n d i a The apparatus about tofb'e described compares the resistance of an unknown or test coir With that ofia genuine" coin and automatically divefts the test'coin' into one char nel' if the coin be gen lime and into another channel if the" coin be counterieit. This coindetecting apparatus may be mounted ih'su'ch'. a position on a coiri vending" machine, that the coin must first pass throu'gh the coin detecting apparatus, be removed from I the coin entrance of the vending machine if the coin" be counterfeit, and be allowed to fa1l'ifito the coin entrahee' of the' vending machine if the chin be genuine". The coin dete'ct'iflg' appa'fa the may also be arranged to" give any sort of audible; visual oi" other signal upon the ifit'rodiidtibn ofa spurious co'in i I j V v Fig'. 1 is a' schematic" diagram of connection's'of the" apparatus'ifFig; 2 is a s'ideele'va'tioxi Of'the' actual-"apparatus omitting the coin holder and theelebt'ric'al Connections to the relays and Contacts. Fig; 3' is a sectional plan view through the lirie 3- 93 as indicated in Fig; 2". Fig; a p1an"vie'wof'the current contact assembly. Figl 5 presentsttvo views'ot the s ring catch on the enc'fiof coin stop plunger; 'Fig. 6 is a sectional end elevation through the line 6-6 as indicated in Fig.2; Figi? is'.'ari,elevatioh of the enuine o'r standaracoin'holder. Fig. sisa plan View of the'genuine or standard co'i'nho'ldei;

Figure 1 presents a connectiondiagramof the either director alternating, is passed through the" genuine or standard coin '1 and the unknown or test coin z' by'means of current' contacts 3 and 4.

- c oinoeteeting"apparatus. Current, which may be gel-a ms; (o1; 19 F) is temporarily held in place by mearis which will'be described later. Current contacts 4 for' the test coin are mouhted'o'n sprizig arms pivoted at ifwhich swing outward, thereby releasii'ig the test coin and breaking the electrical circuit 0 through it; The potential drops across the c'oiiis are measuredby potential, Contacts 5 an'dfi re spectively. Current contacts 3 and the potential contacts 5 for the standard com aie-pem'ianefit- 1y adjusted on the standard coin. Potential coil thfo'ugh the test (Join the testiri'g current gees through time delay trip magnet 21- and then re turns to so'urceflfi'; j I I The potential di ops aeressbothtstandard and test coins are meas'ured by the Kelvin networ as" shown in Fig.1.- The values at the four re:

sistance's mustbe so adjusted that no d'ifierefieo'f poteiitial wil l; eX'is't across the jurietionofresist ance' arms 1Q and 1i and the juhcti'oh of resistance arms 12 and I3 Wher'ithe testing chi'reh't is flowing thiohg'; he' s'tah'dar'd com am a gehmh" e1" words", the resi tances are so 7 when the potehti'ai dropecfos's the test com is equal to'fth peteritial chop' aross" the standard oi'zi,' the"fe will be" no p'ot'e'htial diffe'refie" betwee jlifictibfl of the resistance arms meh'tiohed mate; 'With theiesista ces of arms dfthe'hetwofl so ad'j1istedwhefi the test coin is eouhtei'feit' the phter'itiaf atop across it, that is across potential contacts 6, will be' differentfrohithe pothtiai drop across the sta'n'dafd' c oih that is across potential e'o'ntacts" 5"; this diifer'ende' in potential drops will setup avoltage aer o'ss the' junctiohs of the resistance a ms arid? therebywiil cause a c rrent to flow through te ljayll- Relay 1%- isarlariged' to operatea meeh': anism which causes the apparatus to reject the spurious coin; Atthe same time'itmay be" atr'afigd' to close other circuits to actuateany-k'ind of signaling deviee desi re'bi. Furthermore, if it is so de'sifed',-the ihput terminals of any appropriate voltage? detecting! deviee 'may' he cor'inet'ed across the junctions of the resista be arm's in place of relay- 14 and ar farig'd to ac'tuatea meehahishi to dis'eh ,r'ge the ico'ihsi selectively" dito op'ei'at sig; riaiihg de'vices z- X 4 ,Asshowh'itijFigf 1' however; the e'nergi zirighf re1ay1'4fdiie tothep'resence of 'a eouhterfit coih 15. The movement of armature 15 causes it to close on contact 16 thereby making an electrical circuit through selector magnet 17. The selector magnet then attracts its armature 18, which movement deflects selector vane 19 to such a position that upon release, the spurious test coin will be diverted into the spurious test coin chan nel. On the other hand if the test coin be genuine, relay 14-will remain deenergized; this will keep the circuit through selector magnet 17 open; its armature 18 will therefore remain in its normal or open position which is so arranged that selector vane 19 deflects the genuine coin, it is released, to the genuine coin channel. The test coin is automatically released after a fixed and predetermined length of time by time delay trip magnet 21 which attracts armature 22, The travel of this armature is retarded by an appropriate retarding mechanism 24; at the end of its stroke armature 22 moves trigger 23 tosuch a position that it releases the discharging nism which ejects the test coin into one of two channels depending upon whether the test coin is genuine or counterfeit. The setting of time delay trip magnet 21 is adjusted by retarding mechanism 24for a length of time requisite for the proper functioning of relay 1%; this period is veryshort, being only a fraction of asecond.

. It will be noticed, that when relay 14 is actuated by the presence of a spurious coin between current contacts 4, the voltage across the junctionsof the resistance arm disappears when the coin is released. In order to prevent selector Vane 19 from returning to its normal position before the spurious coin has reached it, selector magnet 17 is provided with a retarding winding 115. The ends of retarding winding 115 terminate in contacts 113 and 114 which are closed and the winding thereby short circuited upon itself by armature 18 when the armature has reached the end of its stroke. Since retarding winding 115 is on open circuit when selector 'magnet 17 is deenergized, the retarding winding does not hinder the fast closing action of the selector magnet. Retarding winding 115 is wound with a sufficient number of turns to pre vent selector vane 19 from returning to its normal position before it has diverted the released spurious coin into the spurious coin channel. In the apparatus to be described, selector vane 19 is mounted immediately beneath the test coin, as a result of which the minimum amount of time elapses between the instant the test coin is released from its current and potential contacts and the instant it strikes selector vane 19.

The apparatus about to be described in detail on the following pages performs the following operations: when a test coin has been dropped into theentrance shute of the apparatus and a plunger depressed, current and potential contacts 4 and 6 close upon the test coin thereby completing a circuit through it, the standard coin and time delay trip magnet 21. Relay 1% is or is not energized depending upon whether the test coin is counterfeit or genuine, which determines the position of selector vane '19. The testing current passing through, time delay trip magnet 21 attracts armature 22 which defiectstrigger 23 at a rate determined by the setting of the retarding mechanism v24. At the end of its stroke trigger 23 releasesthe discharging mechanism which removes the current and potential contacts from the test coin and ejects itinto one of two channels'depending upon the position of selector vane 19. In the actual apparatus dewhen scribed, time delay trip magnet 21, the retarding mechanism 24 and the trigger 23 are incorporated in one unit. If so desired release trigger 23 could be actuated by a separate magnet which in turn would be energized by time delay trip magnet 21.

The use of separate current and potential contacts in this apparatus greatly increases its sensitivity and enables it to segregate counter feit coins whose specific resistance might be very close to that of a genuine coin of the same de- I nomination. At the cost of reduction of sensitivity the current and potential contacts on both standard and test coins could be combined into two pairs of contacts serving both purposes. However, since the object of this apparatus is to provide as sensitive a means of detection as is possible to incorporate in a practical mechanism, separate current and potential contacts have been'provided.

Figure-2 shows the elevation of the test coin receiver and discharger. Resistance.v arms 10,11,

12 and 13 in Fig. 1 as well as the standard coin;

mounted on a suitable. base '79. Thetest coins.

are discharged through discharge shute '65' which passes through the base of the apparatus The lower part of the discharge shute is divided into two channels, one for the genuine coins and one for the spurious coins. These channels may be connected as is desired to. suit the purpose at hand. For instance, in a coin vending apparatus, the discharge channel for good coins could be connected to the coin entrance ofthe coin vending mechanism; the discharge channel for spurious coins could be left open so that the counterfeit coins would simply be rejected by the coin testing mechanism. Test coin 2 is inserted into the top of coin entrance shute 26 as indicated by'arrow 25. The test coin then falls to the bottom of the entrance shute where it is arrested by stop plunger 28 and rests on insulation stop piece 27 which is attached to the end of stop plunger 28. Insulationstop piece 27 is cut into such ashape that it centers the test coin at the by resting on a fiat piece of insulation 41 whichis fastened in a section of the back wall of the ,entrance shute, milled out so that the insulation lies flush with the back wall. Entrance shute 26 is supported. by arm 42 which isan extension of bearing support member 30. The lower part of entrance shute 26 has been shown with the front side of the shuteremoved as indicated by the ir:- regular transverse line. Flexible leads connect the spring arms of current and potential'contacts 4 and 6 respectively as indicated in Fig. 1; to avoid confusing Fig. 2 these connecting leads have been omitted as well as the connecting leads to the trip and selector magnets,

When the test coin falls to the bottom of the entrance chute, in which position it is shown in Fig. 2, vmain plunger 4:0 is pushed in manually against compression spring 51 by depressing plunger handle 52. The inward travel of main plunger 10 causes release catch 60 to pass over release lever trip 59 and lock itself in place.

"magnetic metal.

This is the position shown inFig. 2. Release catch 60 is pivoted to afiat section of main plunger with pin .61; its downward motion is limited by stop pin 62. The same forward motion of the main plunger closes the current and potential contacts upon the'test coin. Potential contacts 6 are'attached to spring'arm's 54 which in turn are mounted on apiece of insulation insulation piece 55'is attached to one end of rocking lever 56 which is pivoted by pin 57 to supportmember 58. The lower endof-rocking lever 56 has a rectangular slot which:engages driving pin64' which is attached to main' plunger. '40. The dimensions of the rocking lever. and the position of pivot pin 57 are such'that when main plunger 49 has been pressed in and, is lockedin position by release catch 60, potential contacts are pressed firmly against the face of the test com. a is Current contacts-4 am closed upon and released from the test coin by the motion of plunger 4? which rides in bearing 53 which is formed by an extension of support member 39. Current contacts 4 are also mounted on spring arms '43 which in turn are fastened to bell crank levers 45 and insulated therefrom by insulating members 44.- The current contact assembly is shown separatelyin Fig. 4. Bell crank levers 45 are pivoted in the upper'part-of support member 30. The offsets 105 and 99-ofbell crank levers 45 are pivoted to connecting links 93 which in turn are connected to the flat section of plunger 47 with pin 100. Offset 105 has a heavier section th'an'oilset 99 so that connecting link 98 attached to-ofiset'l95 can'ride freely-above the connecting 1 40 is'pushed in, itsgbearing disc 49 (Fig. 2)

presses against the tapered endof plunger 47 which acting on the toggle mechanism composed,

of the connecting links 98*and offsets 105 and 99 causes spring arms 43 to press current contacts 4 against the test coin. With the return stroke of main plungerAG bearing disc .49 recedes, current contact plunger 47'is pushed back by its spring 48 and current contacts 4 swing awayfrom the test coin. The outward motion of plunger 47 is arrested by limit stop flange 46.

The forward stroke of main plunger 40 has been seen to close current contacts 4 and potential'contacts 6 upon the test coin, and to lock itself in position against the force of main compression spring 51 by means-of release catch 60. Referring to Fig. l-it is seen that the introduction of test coin closes the circuit through standard coin 1, test coin .2 and time delay trip magnet 21. Trip magnet 21 and its associated time 1 delay mechanism are shownin section through their centers in Fig. 2. The testing current passing through windings of the trip magnetattracts plunger83 against the force of restoring spring v94; attached tothe bottom of plunger 83 is piston 92'which moves in cylinder 87. Trip magnet winding 85 is encased in shell-84 which is made. of magnetic material. Plunger 83 which is also constructed of magnetic material is guided in its travel by bushing 86, which is made of non- Piston 92 being iorceddownwards by plunger -33.expels air ironrcylinderS'? through connection 96 and out through needle .valve 9.3. .The setting of the needle valve determines-the downward rate of travel .of piston '92. order to provide a quick upwardstroke for piston 92, a quick acting air inlet valve 88 attached to the bottom of cylinder .87 byconnection 9 1. An inlet valve 88 has a smooth acting check valve 89 which permits air to enter rapidly into cylinder'87 through orifice 90 when piston 92 is rising, but seals orifice 90 on the downward stroke of the piston when the air seeks egress through connection 91. To prevent restoring spring 94 fromposs'iblyimpeding the progress of the air in and out of the bottom of cylinder 87, the spring is arranged. to rest one. small flangedrpillar 97 provided with holes in the flange,- so disposed that they-fall within the radius of the restoring spring and thereby assure unobstructed passa 0!. air into and from the cylinder. 7

. The upper end of plunger 83 screws on an extension rod 82 which carries driving pin 81, which in turn rides in the yoke at the end of release trip 59. When plunger 83 is attracted downwards it draws release trip 59' down until the release trip releases catch 60, whereupon main plunger spring 51 drives main plunger 40 back to its normal position. With the return stroke of main plunger 40, driving pin 64 engaging rocking lever 55 removes potential contacts 6 from the test coin; likewise bearing disc 49 recedes, allowing compression spring 48 to push is suilicient to enable relay 14 '(Fig. 1) to actuate,

selector magnetv 1'7. I

' Upon the return stroke of main plunger 40, coin stop release lever 3'2, which is fastened to a flat section of the main plunger with pivot pin 39, strikes driving pin 34 which is screwed into pawl Pawl 33 is pivoted to support member 75 with pin 35 and normally maintained in a vertical position by spring 36; The downward motion of coin stop release lever 37 islimited by stop pin 33. The extremity of paw 33 engages spring catch 32, and as pawl 33 is rotated about pin 35 by the action of coin stop release lever 37 on pin 34, coin stop plunger 28' is drawn forward along its' own axis until insulated coin stop 27 is withdrawn sufiiciently from beneath the test coin to allow it to fall into lower or discharge chute 65. Whencoin stop plunger 28 hasbeen withdrawn to this extent, spring catch 32 passes out or" the limiting line of contact with-the extremity 'of pawl 33, is thereby disengaged and restored to its normal position by compression spring 29. The travel of coin stop plunger 28 due to the action of compression spring 29 is arrested by stop flange 31. Since the downward travel of coin stop release lever 37 is limited by stop pin 38, the rotation of pawl 33 lowers driving pin 34 beyond the line of contact with lever 37, whereupon lever 37 releases driving pin 34 and rides over it. Pawl 33 then returns immediately to its vertical position by the action of spring 36. When main plunger 40 is again pushed in for the testing of another coin, coin release lever 37 is free to ride over .pin 34 and drop into position in back of the pin. In order to prevent, interference betweenthe extremity of pawl 33, inreturning to its normal vertical position, and spring catch 32, the catch has been so arranged that it may be deflected sideways, yet normally held in line with coin stop plunger 28 by means of a small leaf spring.

, The construction of the spring catch will be made clear by referring to Fig. 5 which presents two .views of the spring catch on the end of coin stop plunger 28. Catch 32 is pivoted to the fiat extremity 101 of plunger 28 with pin 102 and maintained in alignment with the axis of the plunger by means of leaf spring 103 which presses catch 32 against stop 104. Stop 104 is simply a projection of the fiat extremity 101 of plunger 28. Pawl returning to its vertical position strikes the tapered end of catch 32, deflects the catch to the side and locks itself in back of catch 32 ready for the next stroke.

From the foregoing paragraphs it is now evident that when inain plunger 40 is pushed in, current contacts 4 and potential contacts 6 are closed upon the test coin; that when the main plunger is released by release trip 59, the return stroke of the main plunger releases the current and potential contacts from the test coin, and also withdraws insulated coin stop 27 from beneath the coin. The coin then falls into lower chute 65 which is divided into two channels by partition wall 76. The test coin in falling into the lower chute is diverted into one or the other of the two channels, indicated by arrows 77 and 78, by the position of selector vane 19.

Referring back to the diagram of connections in Fig. 1 it willbe remembered that if test coin 2 be genuine, relay 14 will remain deenergized, which in turn means that selector magnet 17 will not be actuated. Selector magnet in Fig. 2 is mounted on bracket 7 which is attached to support member 75. The armature is in the form of a lever with a yoke at one end and a hole 71 for tension spring 72 at the other. It is pivoted in a yoke cut along the center of the base of the selector magnet by pin 70. Bracket 74 also has a yoke out along its center line far enough in from its extremity to allow tension spring 72 to come up in the yoke and be attached to hole 73, drilled in a projection extending downwards from the base of selector magnet 17. The armature also carries contactor 112 which short circuits the retarding winding (No. 115 in Fig. 1) by closing upon terminal contacts 113 and 114 of the retarding winding when selector magnet 17 is energized and attracts its armature. The yoke in the upper end of the armature engages driving pin 68 which is fastened to the lower end of selector vane 19. Selector vane 19 is made of flat metal sheet and is fastened to pin 66, which serves as the axis of the vane. Shaft or pin 66 for the selector vane rotates in bearings made in the back and front walls of discharge chute 65. Pin 66 extends through the front wall of the chute where it is attached to a crank which carries driving pin 68. To give a clearer picture the front wall of lower chute 65 has been shown removed as indicated by the irregular line near the bottom of the chute. Since, as was assumed at the beginning of this paragraph, the test coin is genuine, selector magnet 17 will not be actuated and tension spring 72 will hold selector armature in the position as shown in Fig. 2. When the coin is released by the removal of current and potential contacts 4 and 6 and by the withdrawal of coin stop plunger 28, it will be deflected by selector vane 19 into the left hand channel as indicated by arrow 78. On the other hand if the test coin be counterfeit, selector magnet 17 will be actuated thereby deflecting selectorvane 19 to the opposite side wall of the chute; the counterfeit test coin upon release is then diverted into the right hand channel as indicated by arrow 77. Selector vane remains defiected to the left hand side of the channel long enough to .divert test coin into the right hand channel indicated by arrow 77 by the action of the retarding winding on selector magnet 17, when the retarding winding is short circuited on itself by contactor 112.

Figure 3 gives a section of the coin receiving and discharging mechanism as seen on line 33 in Figure 2. It will be noticed in Fig.8 that main plunger 40 is bent at point 95 to enable it to pass around discharge chute 65. Main plunger 40 is supported at its ends by bearing members 63 and 50 and also about midway between these members by hearing support member 30, which also carries coin stop plunger 28, the current contact toggle system and extension arm 42 which supports coin entrance chute 26 as may be seen in Fig. 2.

Figure 6 is a section of the coin receiving and discharging mechanism as seen on line 6-6 in Fig. 2. For the sake of clarity rocking lever 56, coin entrance chute 26 and the upper extension of. bearing support member, 30 which supports the coin entrance chute, have been shown vertically instead of inclined as they really are in Fig. 2. Rocking lever 56 which carries potential contacts 6 is pivoted by pin 57 to the left side of the yoke forming the upper part of support member 58. The right hand side of this yoke forms a bearing for release trip 59.

Figures 7 and 8 show two views of the standard coin holder. Standard coin 1 rests on a cylindrical block of insulation 111. Standard coin current contacts 3 are mounted on studs 107 which screw into support blocks 108. Standard coin potential contacts 1 are formed of sharp points turned on the ends of studs 106 which screw into support arms 109. All of these parts are mounted on a suitable insulating base 110. Electrical connections are made by attaching leads to support blocks 108 and support arms 109 as shown in Fig. 1. It should be noted that for the proper functioning of the coin detecting apparatus the standard coin could be replaced by a resistance which would give a voltage drop equal to the voltage drop across a genuine coin when the testing current is passing through it. However, it is usually more practical to use a standard coin holder of the type just described with a genuine coin than to make up an equivalent resistance representing the genuine coin.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A resistance testing apparatus for spurious coins, consisting of a network of six resistances, one arm of which consists of the coin to be tested, a testing circuit, lever-mounted current contacts to pass a current through the coin to be tested, lever-mounted potential contacts to obtain the potential drop across the coin to be tested, a receiving chute provided with a movable stop to support the coin to be tested, a plunger having mechanical connections with the potential and current contact levers and with the movable stop so constructed, that, upon the depression of the plunger, the potential and current contacts are pressed against the coin thereby closing the testing circuit through the coin and. upon release of the plunger the current and potential contacts are released from the coin thereby opening the testing circuit and the movable stop is released from the coin, a time delay solenoid, a catch for engaging the depressed plunger, said catch being released from the plunger by said solenoid after a definite time interval, a relay connected to the resistance network, said relay being actuated when the resistance of the coin to betested is not equal to the resistance of a genuine coin of the same denomination, a discharge chute for tested coins provided with two channels, one for the discharge of genuine coins and the other for the discharge of spurious coins, a deflecting vane in the discharge chute, a time delay selector magnet having an armature connected to the deflect-vane, said selector magnet being connected to the relay so as to operate the deflecting vane when the coin being tested is spurious and maintain the deflecting vane in its operated position until the spurious coin released from the movable stop has been diverted into the spurious coin channel, said deflecting vaneremaining unmoved when the coin being tested is genuine thereby diverting the genuine coin into the genuine coin channel.

2. A resistance testing apparatus for spurious coins, consisting of a network of, six resistances, one arm of which consists ofvthe coin to be tested, another arm of which consists of a genuine coin of the same denomination as the coin to be tested, a testing circuit, lever-mounted current contacts to pass a current through the coin to be tested, lever-mounted potential contacts'to obtain the potential drop across the coin to be tested, cur

rent contacts to pass a current through said genuine coin, potentialcontacts to obtain the potential drop across said genuine coin, a receiving channel.

chute provided with a movable stop to support the coin to betested, a plunger having mechanical connections with the potential and current,

contact levers and with the movable stop so constructed that, upon the depression of the plunger, the lever-mounted potential and current contacts are pressed against the coin to be tested thereby closing the testing circuit through the coin and upon the release of the plunger the lever-mounted potential and current contacts are released from the coin being tested thereby opening the testing circuit and the movable stop is released from the coin being tested, a time delay solenoid, a catch for engaging the depressed plunger, said catch being released from the plunger by said solenoid after av definite time interval, a relay connected to the resistancenetwork, said relay being actuated when the resistance of a coin to be tested is not equal to the resistance of a genuine coin of the same denomination, a discharge chute for tested coins provided with two channels, one for the discharge of genuine coins and the other for the discharge of spurious coins,:a deflecting vane in the discharge chute, a time delay selector magnet having an armature connected to the deflecting vane, said selector magnet being connected to the relay so as to operate the deflecting vane when the coin being tested is spurious and maintain the deflecting vane in its operated position until the spurious coin released from the movable stop has been diverted into the spurious coin channel,

-said deflecting vane remaining unmoved when the coin being tested is genuine thereby diverting the tested genuine coin into the genuinecoin ANATOLI C. SELETZKY. 

